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Hunting henriettas on Ruapuke Island – on the tail of New Zealand’s first mice

Few people are aware of Ruapuke Island. Guarding the eastern approaches to Foveaux Strait, the 1600 ha island is large enough to appear as a smudge of colour at the very bottom of TV3’s weather map. Yet the island’s low relief means that passengers on the Stewart Island ferry 20 km to the west barely notice it compared to the imposing bulks of Bluff Hill and Mt Anglem.

Henrietta Bay on the south coast of Ruapuke Island. The cannon is claimed to have come from the Elizabeth Henrietta. Image: Colin Miskelly

Ruapuke Island is privately-owned, mainly by descendants of the Kai Tahu chief Tuhawaiki. Most of the island is rough farmland (sheep and beef cattle), with a large patch of rimu / rata / kamahi / miro / kahikatea forest in the centre. Long sandy beaches separate granite and basalt headlands, with shallow lagoons lying behind several beaches.

Ruapuke was an important site for two of New Zealand’s earliest industries – the harvesting of fur seal skins and flax (harakeke) fibre. But the island has another more furtive claim to historical fame – or infamy. It was the first New Zealand site to be colonised by mice.

The brig Elizabeth Henrietta was engaged in the flax trade when it ran aground in Henrietta Bay on 25 February 1824. It was eventually refloated in August that year, but some time during its enforced stay, mice made it to shore. This was 6 years before the second recorded presence of mice in New Zealand, at the Bay of Islands in 1830. The residents of Ruapuke Island did not know what the strange creatures were, and reportedly referred to them as ‘henriettas’ after the ship they came from.

A mouse caught on Ruapuke Island. Image: Colin Miskelly

I was privileged to be invited to stay on Ruapuke Island at the tail-end of 2012. My hosts knew the significance of the island’s mice, and had been involved in the collection of tissue samples (i.e. mouse tail tips) for a genetic study that has confirmed that Ruapuke’s mice are from a different lineage to the rest of New Zealand’s mice. Yet during 188 years of mouse presence on Ruapuke Island, no specimens had reached Te Papa’s extensive collection of New Zealand rodents. Prepared with a selection of traps and baits, I spent 3 days trying to rectify this. It took some effort, as the mice were scarce (or wary), with two only caught in 27 corrected trap-nights. The main challenge was hiding the traps from inquisitive weka, which took 4 cheese baits, and would have taken any mice if I didn’t beat them to it.